1. Field of the Invention
The present invention relates to a laminated type heat exchanger, which is suitably employed as a refrigerant evaporator of an automotive air conditioner.
2. Description of Related Art
In a well-known conventional laminated type heat exchanger for an automotive air conditioner, a corrugated fin and a tube element including a pair of symmetrical core plates are laminated to each other. For example, in JP-A-64-41794, and as shown in FIG. 7, the upstream end (with respect to the air flow) 4g of core plates 4 which together form a tube element 2 is spaced from a corrugated fin 3 as shown in FIG. 7, so that condensed water can be drained through corrugated fin 3 and the vent portion can be prevented from being clogged due to the generation of the condensed water.
However, in the structure of tube element 2 disclosed in the above-described prior art, dust and dirt contained in the air passing through a heat exchanging portion enter through a gap 6 between the upstream end 4g of core plate 4 and the upstream end portion of corrugated fin 3 and adhere to tube wall 5a of the refrigerant passage. In this case, when the dust contains some ingredients which promote corrosion of tube wall 5a such as copper particles, tube wall 5a of tube element 2 will corrode causing a refrigerant leak.